Recently, news changes are made in visual surveillance cameras such as CCTV cameras. As an example of the changes, network cameras have emerged.
The network camera is called a web camera. The network camera converts images into digital images, compresses the digital images, and transmits the compressed data through a network based on a high-performance embedded system having a CCD camera therein, so that a user can view the images by recovering the images regardless of locations in real time over the Internet.
In addition, among the network cameras, there exists a network camera connected to a network allowing a user to access the network camera through the network, so that the user can receive images to control the movement of the network camera. The network camera has a unique IP address and a server program installed therein, and a remote user is logged in to a server through the unique IP address of the network camera to receive images from the network camera.
In addition, various schemes have been employed for the network camera in order to remove the dead zone of a surveillance region. One of the schemes is based on a fisheye lens, and another scheme is based on a lens equipped with a pan-tilt function.
However, if the fisheye-based lens is employed, a distortion phenomenon may be caused by a short focal length. If the scheme based on the lens equipped with the pan-tilt function is employed, a complex circuit to perform panning and tilting may be required. Accordingly, schemes to effectively remove the dead zone of the network camera are required.